Supervisory system for telephone-lines.



W. W. DEAN.

SUPERVISORY SYSTEM FOR TELEPHONE LINES.

APPLICATION FILED JUNE 15, 1903.

1 9 1 45,760 Patented July 13, 1915.

mere.

WILLIAM W. DEAN, OF QI-IICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITCHBOABD & SUPPLYCOMPANY, OF CHICAGO, ILLINOIS, AYGORPORATION OF ILLINOIS.

SUPERVISORY SYSTEM FOR TELEPHONE-LINES.

Application filed June 15, 1.963.

To all whom it may concern:

Be it known that I, WILLIAM DEAN, a citizen of the United States of America, and resident of Chicago, county of Cook, Stateof Illinois, have invented a new and useful Improvement in Supervisory Sys tems for Telephone-Lines,of which-the following is a specification.

My invention relates to improvements in telephone systems, more particularlyin supervisory apparatus, my object being to provide an apparatus which is simpler than that ordinarily employedto accomplish the same results. My supervisory system is particularly applicable to what is commonly termed two wire 7 systems, that is, systems employing .only ,two wires in the switchboard section of the line and two strands in'the cord circuit, and at thesame time a common source, of current at thecentral oiiice furnishes current to the substations for talking purposes.

, Myinventionoperates upon what may be termeda marginal system. That is the initial operation of the device is controlled by certain resistances and the further operation of the same is causedrby a reduction of saidresistances or by an increased flow of current throughthe coils of saiddevice. In the supervisory apparatus for instance, the lnsertion of the plugin an idle'line operates the device far enough to cause the associated supervisory signal to-be operated and the reponse of the called subscriber or the completion of the line circuit to current thereover causesthe furtheroperation ofthe device to efface said signal.

In the accompanying drawing, which illustrates the invention, Figure 1 is a diagram of a system embodying one form of my improvements, and Fig. 2 is a diagram of a modification.

In Fig. 1, Land L representsubscribers lines extenclingin two limbs 2 and 3 from the respective substations to the central office. At the substationa call bell 4 and condenser 5 are placed iii-abridge of the line conductors, while a -transmitter 6 and receiver 7 are locatedin a bridge normally open at the switch-hook 8. This substation apparatus is intended merely to typify any usual or desired common battery outfit. At the central oflice the line is fitted Specification of Letters Patent.

Patented July 13,1915.

Serial Ho. 161,532.

with the usual answering and multiple jacks J, J and J and with the line signal S the local circuit of which is controlled by ,the two movable contacts of said relay are adapted to disconnect from their normal connections and complete the circuit of the line conductors-2 and 3 to the correspond ing ,contacts of the jacks. Each operator istprovided with a number of cord circuits one only being shown, each including an answering plug P and a calling plug P having tip and sleevecontacts adapted to register withthe corresponding contacts of the acks ofthelines. The tip contacts of these plugs are connected by flexible strands .z and t and the interposed condenser 0,

whilethe sleeve contacts are joined by the strands s and ,8 and the interposed condenser 0?. The battery B is bridgedacross the ,answeringend of the cord circuit and includes upon the .tip side thereof the impedance coil .10 and upon the other side .the supervisory relay 7". This relay is provided with a .movable contact 11 which is acted upon by a Weight 12 or other suitable device and carries a preferably adjustable contact 13. This latter contact is adapted .to engage with a contact mountedupon the pivoted arm 14; which is also provided with a Weightsuch as 15 or other suitable device; and asecond contactcarried by said arm is .adaptednormally to engage theadjustable stationary contact l6,the latter being joined tothe grounded pole of the battery B by a suitable conductor 17 while the armature 11 of said relay 7" is connected by conductor 18 with the live pole of said' b attery and includes a suitable supervisory signal S preferably in the form of a small incandescentlamp. The resistance through whichthe said relay .1Kis intended to operate .is such thatthe armature 11 is first attracted until ,it engages the movable contact 14: but is not sufficiently energized at this stage of the operation to press said movable contact 14:

away from the stationary contact 16. It is therefore seen that the local circuit of the supervisory lamp S is at this time com pleted; but upon a further flow of current through the relay 7- which will occur as hereinafter pointed out, the armature 11 is attracted with sufficient force to move the lever 1A away from the stationary contact 16 to thereby open the circuit of the lamp S which is acordingly extinguished.

Across the calling end of the cord circuit I a battery 13 is connected through the impedance coil 19 and the relay 1' corresponding to the relay r upon the other side of the cord circuit, said latter relay controlling through similar devices the local circuit of the supervisory lamp S The operators receiver 20, the secondary of her induction coil 21 and the condenser 0 are adapted to be bridged across the calling end of the cord circuit in the usual manner while the transmitter 22 is fed from battery in the ordinary manner. A calling generator 23 is adapted to be connected with the tip side of the cord circuit by the operation of the tip ringing spring 24:, while the sleeve side of the cord is simultaneously connected through a branch conductor 25 and a suitable resistance 26 directly with the battery B In the operation of this form of the invention a subscriber calls in the usual manner by taking up his receiver thereby completing a path for current over his metallic line and operating his line signal S. Upon observing the signal the operator inserts the answering plug P of the cord circuit thereby completing a path for current from the live pole of the battery B, through the relay 1', strand 8 of the cord circuit and the sleeve conductor of the jack section of the line and the winding of the cut-off relay R to ground. The current in this path is suflicient to operate said cut-off relay to disconnect the line conductors from their normal contacts thereby extinguishing the line signal and to connect them with the switchboard section of the line to thereby place the line in condition for conversation. The current in this path is also suflicient to operate the supervisory relay 1" to cause it to close its contact 13 against the lever 14 and only suflicient for this purpose if the subscribers telephone were not in use whereby the supervisory signal S would be operated; but owing to the fact that the subscribers telephone is in use, the path for current is completed over the telephone line and through the tip strand of the cord circuit to the other pole of the battery. The line circuit being in parallel with that of the cut-off relay R causes a sufficient reduction in resistance to the passage of current through the relay 0" to cause an increased current flow therethrough thereby completely operating it to open the local circuit of said signal at the contact 16. This signal is accordingly inert at this stage of the connection.

Upon connecting her telephone with the line and learning the order for the connection the operator proceeds to test the condition of the wanted line. If idle, the test contacts of the lines are connected with ground through the cut-off relay and since the tip of the testing plug is likewise grounded no flow of current takes place and no click is received. Assuming that the line is busy, however, the said test rings are connected with either the battery B or B and the application thereto of the grounded tip of the testing plug results in a flow of current over the strand t of the testing cord and a click is received in the operators re ceiver to indicate to her that the line is busy.

Assuming that the line is found idle, the calling plug P is inserted in the jack of the line and the ringing generator operated. The cut-off relay is maintained operated during ringing by current from the battery B over conductor 25 even though the sleeve strand is severed by the sleeve spring of the ringing key 24. After calling the subscriber and before his response current from the battery B is flowing through the supervisory relay 1 over the strand 8 and through the cut-off relay R of the called line. The resistance of the supervisory relay 1 is so proportioned that it will merely close contact 13 but will not move arm 14 away from contact 16. This adjustment is readily obtained for the reason that only constant resistances are encountered. For example, the resistance of the cut-off relay R is constant, the resistance of circuit for any line is the same, and the voltage of the battery is constant, so that the desired operation of the supervisory relay 7 may be readily obtained. The local circuit of the supervisory lamp S is therefore closed and the lamp lighted to indicate to the operator that the subscriber has not yet responded. As soon as he responds, however, current from the battery B circulates over the metallic line, and causes a considerably increased flow of current over the strand s of the cord circuit and through the supervisory relay 0. The said relay 1* is further adjusted to respond to this increased current and therefore moves contact 1 1 away from contact 16, to open the local circuit of the supervisory signal S thereby extinguishing it.

During conversation current is flowing from the batteries B and B over the telephone lines, the voice currents being prevented from short circuiting across the cord circuit by means of impedance coils l0 and 19 and the relays r and r and being repeated from one line to the other by the condensers c and 0 At the termination of the conversation the return of the subscribers receivers to their hooks serves to decrease the flow of current through the supervisory relays 1" and T which accordingly allow the movable contacts 14; to close against the stationary contacts 16 thereby again closing the local circuits of the supervisory lamps S and S which are lighted to indicate to the operator the termination of the conversation. Upon observing these signals she withdraws the plugs from the jacks of the telephone lines thus restoring all parts to normal condition.

In Fig. 2 the margin of operation of said supervisory relays r and r is increased. This is accomplished by dispensing with the impedance'coils 10 and 19 of Fig. l and putting extra coils upon the cores of said magnets rand 1, these being indicated at 27 and 28. When, therefore, the telephone at the subscribers station is removed from the hook the current flowing to the grounded pole of: the battery passes first through the said additional coils 27 and 28. This effect is added to that of increasing the current flow through the other coils as described with reference to Fig. 1, since it is apparent that the same increased flow of current now results as before and that the sleeve windings of said relays are efiected in the same manner. This latter arrangement tends to render the action of said relays more positive.

I claim 1. In a telephone system, the combination with a telephone line, of a cord circuit to establish connections with the line for conversation, a line signal, a cut-ofi relay for the line adapted to render the line signal inoperative when a connection is established, a supervisory relay associated with the cord circuit, means for establishing a path for current through said supervisory and cutofl? relays when a connection is established with the line to simultaneously operate the cut-off relay and to partially operate the supervisory relay, a supervisory signal having its circuit closed during such period of partial operation of the supervisory relay, and means whereby when the subscribers telephone is in use an increased How of current through said supervisory relay completely operates the same and thereby renders the supervisory signal inoperative, substantially as described.

2. In a telephone system, the combination with a telephone line, of a cord circuit to establish connections for conversation therewith, a supervisory relay associated with the cord circuit, a central source of current to furnish current over the telephone line for conversation, said relay being partially operated during the connection when the subscribers telephone is not in use to operate the supervisory signal, and an additional winding upon said relay in the path of current over the telephone line when the telephone is in use, said additional winding assisting in the complete energization and operation of said relayto renderthe supervisory signal inoperative, substantially as described.

3. In a telephone system, the combination with a telephone line, of a cord circuit to establish connections with the line for conversation, a line signal, a cut-oil device for the line adapted when operated to render the line signal inoperative, a supervisory signal controlling magnet associated with the cord circuit, a suitable signal adapted to be controlled thereby, means for establishing a path for current through said magnet and said cut-off device when a connection is established with the line for conversation, the current in said path when the subscribers telephone is upon its hook being only suilicient to simultaneously operate the cut-off device to efiace the line signal and said magnet in such manner as to cause the latter to disclose its signal, and means whereby when the subscribers telephone is in use a low resistance path is proto vided for current through said magnet which is more completely energized thereby and serves in this condition to et'face the supervisory signal, substantially as described.

l. In a telephone exchange system, the combination of a subscribers line free from opera tive earth connections outside of the exchange,

a link conductor associated therewith, a nonpolarized electromagnet, a normally efiaced supervisory signal and a source of current all associated with said link conductor, a path under the control of the operator for causing a flow of current through said mag net to cause the display of said signal, a branch ,path for current directly controlled by the subscriber when said link conductor is connected with said line and means for closing both branches contemporaneously to cause the eltacement of said signal by increasing the energization of the said magnet, substantially as described.

5. A telephone system comprising telephone lines, cord circuits for interconnecting said lines, supervisory relays for the cord circuit, means responsive to connection of a cord circuit with an idle called line to establish an energizing circuit for the supervisory relay whereby it is partly operated to display a signal, a second winding for the supervisory relay, and means for establishing an energizing circuit through the second winding upon response from the called substation to ellect an increased energization of the supervisory relay for eflacing the signal.

6. A telephone system comprising tele phone lines having line jacks and cut-off relays, cord circuits for interconnecting said lines, supervisory relays for the cord circuit, a source of current, means responsive to connection of a cord circuit With an idle called line to establish a circuit for the supervisory and cut-off relays whereby the cut-off relay is operated and the supervisory relay is partly energized to display a signal, and means for establishing an additional energizing circuit for the supervisory relay upon response from the called substation and maintaining the initial and additional circuits to effect an increased energization of the supervisory relay for efiacing the signal.

7. A telephone system comprising telephone lines having cut-oli relays, cord circuits for interconnecting said lines and hav ing supervisory relays, a source of current having one of its poles connected to a terminal ofthe supervisory relay and its other pole connected to a terminal of the cut-off relay, means responsive to connection of a cord circuit to a telephone line to connect a supervisory and a cut-01f relay in series whereby said cut-off relay is operated and the supervisory relay partly operated to display a signal, and means at the connected substation for establishing and maintaining Copies of this patent may be obtained for a further operation thereof to efi ace the signal.

8. A telephone system comprising telephone lines, cord circuits for interconnecting said lines, supervisory relays for the cord circuit, means responsive to connection of a cord circuit with a telephone line to establish an energizing circuit for the associated supervisory relay whereby it is partly energized to display a signal, and means controlled at the connected substation for adding to the first energizing circuit of the supervisory relay in its initial direction to cause an increased energization and magnetization of the supervisory relay to eliect a further operation thereof for eilacing the signal.

Signed by me at Chicago, county of Cook, State of Illinois, this 12th day of June, 1903.

W'ILLIAM W. DEAN. l/Vitnesses:

GAZELLE BEDER, ROBERT LEWIS AMEs.

five cents each, by addressing the Commissioner of E's/cents,

Washington, I). G. 

